Emanuel urges Chicagoans to take cold 'seriously'

He says the city is experiencing some of the "most extreme weather" in decades, and urges people to stay indoors and check on their elderly or disabled neighbors.

The mayor spoke at a news conference Monday, where the head of Chicago Public Schools announced that classes would be canceled Tuesday for a second day.

Social services workers also will be on the streets looking for homeless people and conducting well-being checks on shut-in residents. A dozen warming centers will be open to residents on Tuesday, as will park district buildings, police stations and libraries.

The National Weather Service says temperatures are again expected to dip to 16 below zero overnight with wind chills of minus 40.